Staying cool in the nanoelectric universe by getting hot

A University at Buffalo study hints that, to make laptops and other portable electronic devices more robust, more heat might be the answer. Here, nanoconductors squeeze an electrical current into a narrow channel, increasing the amount of heat circulating through a microchip’s nanotransistor. Credit: Jon Bird and Jong Han.

Research hints that nanodevices in microcircuits can protect themselves from heat generation; could boost computing power without large-scale changes to electronics

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“We’ve found that it’s possible to protect nanoelectronic devices from the heat they generate in a way that preserves how these devices function.”

Jonathan Bird, professor of electrical engineering

University at Buffalo

BUFFALO, N.Y. – As smartphones, tablets and other gadgets
become smaller and more sophisticated, the heat they generate while
in use increases. This is a growing problem because it can cause
the electronics inside the gadgets to fail.

Conventional wisdom suggests the solution is to keep the guts of
these gadgets cool.

But a new University at Buffalo research paper hints at the
opposite: that is, to make laptops and other portable electronic
devices more robust, more heat might be the answer.

“We’ve found that it’s possible to protect
nanoelectronic devices from the heat they generate in a way that
preserves how these devices function,” said Jonathan Bird,
professor in UB's Department of Electrical Engineering and a member
of the department's solid-state electronics research group.

He continued: “This will hopefully allow us to continue
developing more powerful smartphones, tablets and other devices
without having a fundamental meltdown in their operation due to
overheating.”

The paper, “Formation of a protected sub-band for
conduction in quantum point contacts under extreme biasing,”
was published Jan. 19 in the journal Nature Nanotechnology. It is
available at the following link:http://bit.ly/1ikkkHg.

Bird is the co-lead author along with Jong Han, associate
professor UB's Department of Physics and a member of the
department's theoretical condensed matter research group.

Contributing authors are Jebum Lee and Jungwoo Song, who both
recently earned PhDs in UB's Department of Electrical Engineering;
Shiran Xiao, PhD candidate in electrical engineering at UB; and
John L. Reno, Center for Integrated Nanotechnologies at Sandia
National Laboratories.

Heat in electronic devices is generated by the movement of
electrons through transistors, resistors and other elements of an
electrical network. Depending on the network, there are a variety
of ways, such as cooling fans and heat sinks, to prevent the
circuits from overheating.

But as more integrated circuits and transistors are added to
devices to boost their computing power, it’s becoming more
difficult to keep those elements cool. Most nanoelectrics research
centers are working to develop advanced materials that are capable
of withstanding the extreme environment inside smartphones, laptops
and other devices.

While advanced materials show tremendous potential, the UB
research suggests there may still be room within the existing
paradigm of electronic devices to continue developing more powerful
computers.

To support their findings, the researchers fabricated nanoscale
semiconductor devices in a state-of-the-art gallium arsenide
crystal provided to UB by Sandia’s Reno. The researchers then
subjected the chip to a large voltage, squeezing an electrical
current through the nanoconductors. This, in turn, increased the
amount of heat circulating through the chip’s
nanotransistor.

But instead of degrading the device, the nanotransistor
spontaneously transformed itself into a quantum state that was
protected from the effect of heating and provided a robust channel
of electric current. To help explain, Bird offered an analogy to
Niagara Falls.

“The water, or energy, comes from a source; in this case,
the Great Lakes. It’s channeled into a narrow point (the
Niagara River) and ultimately flows over Niagara Falls. At the
bottom of waterfall is dissipated energy. But unlike the waterfall,
this dissipated energy recirculates throughout the chip and changes
how heat affects, or in this case doesn’t affect, the
network’s operation.”

While this behavior may seem unusual, especially conceptualizing
it in terms of water flowing over a waterfall, it is the direct
result of the quantum mechanical nature of electronics when viewed
on the nanoscale. The current is made up of electrons which
spontaneously organize to form a narrow conducting filament through
the nanoconductor. It is this filament that is so robust against
the effects of heating.

“We’re not actually eliminating the heat, but
we’ve managed to stop it from affecting the electrical
network. In a way, this is an optimization of the current
paradigm,” said Han, who developed the theoretical models
which explain the findings.

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